1. Field of the Invention
The invention concerns an apparatus, method and kit for removal of polyps from internal organs, especially the colon, of a human body.
2. Related Art
Colonoscopic polypectomy is a very common endoscopic procedure (Gillespie et al., GUT 20:240, 1979; Panish, Am J. Gastroenterol, 71:315, 1979; Shinya and Wolff, Ann Surg 109:679, 1979; Knutson and Max, Arch Surg, 114:440, 1979). The purpose of endoscopic polypectomy is to remove polyps from the colon that are detected during colonoscopy or other screening procedures. Illustrative of this technology are the disclosures found in U.S. Pat. No. 4,905,691; U.S. Pat. No. 5,158,561; and U.S. Pat. No. 5,540,683. Polypectomy is performed by passing a stainless steel wire loop through the colonscope (known as a snare) and placing it around the polyp. The loop is tightened and electrical energy is applied to the snare. Electrical energy is then transmitted to the tissue and converts to heat. Water in the tissue thereby heats up causing cells to explode resulting in coagulation and a cutting effect, separating polyp from tissue. The snare is then closed manually by the endoscopic assistant or the physician completing the polypectomy process.
Routine endoscopic polypectomy has a very high success rate and a very low complication rate. However, when the physician is confronted with sessile or thick stalked polyps, the procedure of endoscopic polypectomy becomes more challenging. In these cases, the limitations of the present technique of endoscopic polypectomy become apparent. First, the force applied while closing of the snare is a highly subjective action of the surgeon, performed in a highly uncontrolled manner. Secondly, the rate of resection during the electrical coagulation is typically an overlooked parameter which may significantly affect success of the operation. There are currently no indicators to guide the physician as to how fast and under what force to close the snare. In the absence of such an indication, undesired complications may take place. These complications may include excessive bleeding where the resection process proceeds too rapidly and there is insufficient coagulation of the underlying blood vessels. Alternatively, perforation of the GI tract may occur when excessive energy is applied to the tissue. (Fruhmorgen, Colonscopy, Chapman and Hall, 1981).
Accordingly, it is an object of the present invention to provide an apparatus, kit and method for performing a polypectomy that avoids surgical complications such as excessive bleeding and/or perforation of the gastrointestinal tract.
We propose that a key parameter in avoiding complications of polypectomy is temperature control of cutting edges forming the snare. Temperature sensors are provided to the area of the snare near and/or along the cutting edge, to indicate and control the resection process. Information gathered in monitoring temperature of that area is used for controlling the electrical coagulation in the endoscopic polypectomy.
The current invention is superior over prior art in the sense that resection is performed in a controlled manner. More specifically, the snare temperature is set as the controlled parameter of resection. It is commonly accepted that resection is preferable only above some threshold temperature of the snare""s cutting edge but that too high temperatures are highly likely to involve complications.
Temperature control is achieved by the application of temperature sensors. Two preferred embodiments of the present invention involve: (i) an open-loop control system, where the operator/physician controls the electrical power supplied to the snare, in order to maintain temperatures in some working temperature range; and (ii) a close-loop control system, where an independent automatic temperature controller is applied to maintain some desired and pre-specified temperature above the threshold temperature.
Based on the foregoing discoveries, we provide an apparatus for polyp removal which includes:
(i) an endoscopic guide tube;
(ii) a heating element;
(iii) a power transmitting element traversing through the guide tube and communicating with the heating element; and
(iv) at least one temperature sensor for measuring temperature near the polyp.
Preferably present will be a temperature controlling element for receiving temperature information from the sensor and then signaling a power source for adjusting the temperature of the heating element. Another useful component is an electrical power/temperature sensor synchronization device for deactivating the applied electrical power during periods of temperature measurement.
A kit for polyp removal is also provided utilizing the aforementioned apparatus and including instructions accompanying the kit for deploying the apparatus. The instructions recite the following steps:
(A) providing an endoscopic apparatus which features (i) through (iv) as mentioned above;
(B) inserting the endoscopic guide tube into a human body;
(C) deploying the heating element to surround a polyp; and
(D) energizing the heating element in a temperature controlled manner.